Manufacturing, Processing, Packing, and Holding of Human Food
3.2 Potential Hazards
3.3.5 Potential Facility-Related Biological Hazards
3.3.5.3 Facility-related environmental pathogens associated with wet vs
dry processing environments
Food processing operations can typically be classified into one of two simple categories – wet processing environments or dry processing environments (Table 3-5). This very simple
distinction has significant implications for the strategy that must be applied to control food contamination from environmental pathogens.
Table 3-5. Some Examples of Foods Processed in Wet and Dry Processing Environments
Processing Environment Conditions
Examples of Foods
Wet • Ice Cream
• Refrigerated Dairy Products
• Refrigerated Deli Salads
• Refrigerated and Frozen Meals
• Refrigerated Beverages (non-juice) Dry • Chocolate and Confections
• Milk Powders
• Baked Goods
• Dehydrated Soups
• Powdered Beverages
• Nut/nut products
3.3.5.3.1 Wet process environments
The most effective strategy to prevent the contamination of finished products with L.
monocytogenes is to maintain an environment as dry as possible. Wet environments have some very obvious characteristics that lead to problems with contamination by L. monocytogenes, such as:
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• Wet floors can create harborage sites if they are not well maintained and have broken/cracked grout or tiles. These structures may provide protected harborage to environmental pathogens even when the floors are cleaned and sanitized.
• Condensation on overhead structures as a result of air temperature and humidity control issues and from use of water in cooking and cooling operations creates a means of transfer of Listeria spp., including L. monocytogenes, from non-food-contact surfaces to exposed product and equipment food-contact surfaces.
• Frost formation due to condensation at freezer entry and exit points provides an opportunity for moisture accumulation and a constant source of water for Listeria spp. to multiply.
• Inadequate sanitation practices on floor freezer and cooler units may provide the moisture to support Listeria spp., including L. monocytogenes, if water sources are not properly
plumbed to hygienically designed drains.
Wet floors can serve as vectors for spreading Listeria spp. via the movement of people and equipment and material handling items such as totes and pallets. Wet floors can also serve as vectors for pathogen transfer when personnel walk through standing water on poorly designed floors and drains and during cleaning. L. monocytogenes does not spread alone through the air;
however, in wet environments, aerosols from high pressure water hoses used during cleaning operations help spread L. monocytogenes throughout the environment and from one surface (e.g., floors) to another surface (e.g., food contact surfaces, such as conveyors, tables, and product containers). In many facilities, certain processing operations are inherently wet, such as product debagging, raw material preparation, mixing and formulation of liquid product
components, cooking, and blanching. In these cases, the best that can be done is to control the personnel, equipment traffic, and cleaning practices that are involved with the specific operation.
The intent is to minimize water accumulation and aerosol formation to prevent in-process and finished product recontamination.
We recommend that wet processing areas be dried out as much as possible. This continues to be an ongoing challenge for the food industry that has for many years depended upon the unlimited use of water for equipment and facility cleaning practices.
3.3.5.3.2 Dry process environments
Moisture control is critically important in preventing Salmonella contamination in low-moisture products (ICMSF, 2005). Water in the dry processing environment is one of the most significant risk factors (perhaps the single most important factor) for Salmonella contamination, because water allows for pathogen growth, significantly increasing the risk for product contamination.
Water, present even in very small amounts for short, sporadic time periods, may allow Salmonella to grow in the environment. At times, moisture is obvious in the form of water droplets or puddles from wet cleaning or from other not-so-apparent sources such as high relative humidity or moisture accumulating inside of equipment.
Salmonella can, to varying degrees, be introduced into low-moisture product manufacturing facilities and become established in those environments. Harborage sites may develop and become a source of product contamination, unless the sites are identified and eliminated (CAC, 2008).
available to microorganisms. Growth cannot occur, however, if the plant environment is
sufficiently dry. The potential Salmonella harborage sites become more important when water is present for a sufficient period of time. The presence of water in the dry processing environment can result from improper use of water during cleaning, which has been linked to the occurrence and spread of Salmonella (CAC, 2008). Other events resulting in the presence of water in a dry area include condensate formation, leaking water or steam valves, infiltration of water following heavy rains (e.g., leaky roofs) and the use of water showers in the case of fire emergencies.
(CAC, 2008). We recommend that you remove water immediately from the primary Salmonella- controlled hygiene areas (areas where RTE food is exposed to the environment) following such events in order to keep the plant environment as dry as possible.
You should maintain dry conditions at all times in primary Salmonella-controlled hygiene areas, except for the occasions when you have determined that controlled wet cleaning is necessary.
Potential problems arise when there is visible water present in the dry areas or when there are areas in which standing water has dried out. Salmonella may be found both in wet spots and in spots where standing water has dried (Zink, 2007). The latter situation may present an
additional risk of spread via the generation of airborne contaminated dust.
3.4 Chemical Hazards
You must conduct a hazard analysis to identify and evaluate known or reasonably foreseeable chemical hazards. See 21 CFR 117.130(b)(1)(ii). When your hazard analysis identifies a known or reasonably foreseeable chemical hazard that requires a preventive control, you must identify and implement a preventive control for the chemical hazard. See 21 CFR 117.135(a)(1).
The chemical hazards that are the focus of this section of this chapter include ingredient-related chemical hazards (i.e., pesticide and drug residues, heavy metals, environmental contaminants, histamine due to decomposition, natural toxins (e.g., mycotoxins), radiological hazards,
unapproved food and color additives, food allergens, and substances associated with a food intolerance or food disorder) and process-related chemical hazards (i.e., food allergens, substances introduced by misformulation and the introduction of industrial chemicals or other contaminants from the food processing environment).
Food products can become contaminated with chemical hazards that are introduced at any stage in food production and processing. Some ingredient-related chemical hazards are natural components of food, such as food allergens, or are produced in the natural environment, such as mycotoxins, whereas other ingredient-related hazards (e.g., pesticides, drug residues, heavy metals, environmental contaminants) are contaminants of raw materials and other ingredients.
Some process-related chemical hazards may be included in product formulation (e.g., sulfites that are a hazard for those consumers who are sensitive to them), whereas other process- related chemical hazards may be unintentionally introduced into food, such as industrial chemicals that are used in a facility for purposes other than food production. Process contaminants may also form during heating (e.g., acrylamide).2 For further details on the
2 Some processing contaminants are formed during the heating of certain ingredients or finished foods (e.g., acrylamide). We have not included such contaminants in Table 3-6 as potential process-related chemical hazards that may require a preventive control as part of a food safety plan under part 117 because we believe that more information is needed regarding appropriate levels and effective controls.
As stated in our “Guidance for Industry: Acrylamide in Foods” (FDA, 2016a), we recommend that
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A chemical hazard may cause immediate effects, or may be associated with potential long-term effects after chronic exposure to the chemical. One example of an immediate effect is
gastrointestinal illness such as nausea, which can be caused by elevated levels of industrial chemicals (such as caustic cleaning compounds). Caustic cleaning compounds can also cause burning of the mouth and esophagus. Ammonia in food contaminated by a refrigerant leak has caused gastrointestinal illness (stomachache and nausea) and headaches (Dworkin, et al.
2004). Sulfites have resulted in diarrhea, headache, difficulty breathing, vomiting, nausea, abdominal pain and cramps in sulfite-sensitive individuals (Timbo et al. 2004). Examples of long-term effects include impaired cognitive development in children chronically exposed to relatively low levels of lead (e.g., in contaminated candy) (FDA, 2006a) and liver cancer
resulting from chronic exposure to the mycotoxin, aflatoxin (Williams et. al, 2004 and Shephard, 2008).
FDA has set action levels and tolerances for some contaminants (FDA, 2015f). They represent limits at or above which FDA will take legal action to remove products from the market. Where no established action level or tolerance exists, FDA may take legal action against the product at the minimal detectable level of the contaminant. Action levels and tolerances are established based on the unavoidability of the poisonous or deleterious substances and do not represent permissible levels of contamination where it is avoidable. For example, FDA has established an action level of 3 ppm polychlorinated biphenyl (PCB) residues in red meat on a fat basis (FDA, 1987). FDA also has issued for public comment a draft guidance for industry that would, when finalized, establish an action level of 100 ppb for inorganic arsenic in infant rice cereal (FDA 2016). FDA has established tolerances for polychlorinated biphenyls (PCB's) in foods such as milk and other dairy products, poultry, eggs, and infant and junior foods (see 21 CFR 109.30).
Further, under the Federal Food, Drug, and Cosmetic Act (FD&C Act), certain substances, such as food additives, color additives, new animal drugs, and pesticides require premarket approval before they may be legally used.
FDA also has issued guidances to provide information to industry on methods to reduce levels of specific chemicals in foods. For example, FDA has issued guidance providing information to help growers, manufacturers, and food service operators reduce acrylamide levels in certain foods (FDA, 2016a). Similarly, the Codex Alimentarius Commission has established a number of codes of practice for controlling mycotoxins, heavy metals, and other chemicals in foods (CAC, 2012).
Chemical residues in a food are not always considered hazards and their occurrence may be unavoidable. Because the particular chemical and its levels in the food determine whether it is a hazard, and because mechanisms whereby a chemical hazard can be introduced into a food product are both varied and dependent on the nature of the chemical, the preventive controls that you identify and implement to control specific chemical hazards should be based on the characteristics of those chemicals and the mechanisms whereby they could be introduced into your food product. In the following sections on chemical hazards, we describe some common preventive controls for controlling chemical hazards. For additional information on the control of manufacturers evaluate approaches to acrylamide reduction that may be relevant to their particular processes and consider adopting approaches, if feasible, that reduce acrylamide levels in their products.
In the remainder of this section on chemical hazards, we briefly describe characteristics of some chemical hazards that are of concern in foods and processing environments, including
mechanisms whereby they can be introduced into a food product. We do not discuss seafood toxins in this guidance because seafood is exempt from the PCHF requirements; for a
discussion of seafood toxins see our Fish and Fishery Products Hazards and Controls Guidance (FDA, 2011).
Table 3-6 is a quick reference guide to help you identify some of the most common sources of chemical hazards; Table 3-6 does not provide an exhaustive list of such hazards
Table 3-6. Quick Reference Guide for Common Sources of Chemical Hazards
Source Examples
Ingredient-related chemical hazards • Pesticide residues on produce raw agricultural commodities
• Drug residues in milk
• Heavy metals in or on produce raw agricultural commodities
• Environmental contaminants (e.g., dioxins)
• Mycotoxins in grains
• Histamine in some aged cheeses
• Radiological hazards in foods from areas after a nuclear accident
• Unapproved food or color additives
• Food allergens and substances associated with a food intolerance or food disorder (e.g., sulfites, gluten) Process-related chemical hazards • Undeclared food allergens due to mislabeling or cross-
contact
• Improper addition of substances associated with a food intolerance (e.g., sulfites)
• Improper use of a color additive such as Yellow No. 5
• Contamination with industrial chemicals such as cleaners or sanitizers
• Radiological hazards from use of contaminated water supply
Facility-related chemical hazards • Heavy metals due to leaching from equipment, containers, or utensils
3.4.1 Ingredient-Related Chemical Hazards